1. Field of the Invention
The invention relates to a plastic layer that has release properties towards adhesives and/or adhesive materials.
2. The Prior Art
Layers with release properties towards adhesive or adhesive materials generally consist of silicone and are applied to a plastic film or a similar substrate in a separate operation.
The purpose of the invention is to provide these release properties earlier, in the course of the production process.
This problem is solved according to the invention by incorporating the materials that produce the release properties in the plastic layer so that the materials can be extruded with the plastic layer.
This not only facilitates production very considerably; the level of the release properties is easy to set as well.
In accordance with an advantageous further development of the invention, the basic polymer or material is provided with modified properties, as a result of which the release properties are achieved.
The required strength of the release properties can be taken into account during production of the basic polymer.
In another advantageous further development of the invention, the release additive incorporated is based on silicone compounds.
The level of the release properties can be controlled very easily when the additive is incorporated in this way too.
It is also very advantageous if in accordance with another further development of the invention substances similar to polyolefins are incorporated as release additives.
All of these developments make sure that the materials with which the release properties are achieved only migrate into the adhesive to an insignificant extent if at all.
It has also been proved to be very advantageous if the release additives are incorporated in the plastic during polymerization.
In another advantageous development, the release additives are embedded firmly in the plastic matrix.
In a further advantageous development of the invention, fillers that are, for example, structured as inorganic compounds are provided as release additives.
It has proved to be particularly advantageous in production of the plastic layer if the layer is manufactured from a masterbatch.
In this case, the masterbatch can contain a consistent proportion of the release additives; the final percentage accounted for by the release material is then determined by the plastic-to-masterbatch mixing ratio.
In a further embodiment, the release material may be mixed into the basic polymer material so as to concentrate the release materials on the surface of the basic polymer. The release materials are based on organo-silicone graft polymers and/or organo-silicone block copolymers obtained from mercapto-functionalized silicones, in particular polydimethyl-siloxanes. These are produced by modifying SiH-containing polysiloxanes with organic, polymerizable monomers of the type that can be produced with acrylates, for example with methylmethacrylate or butylacrylate or styrene or vinyl acetate.
The plastic layer in accordance with the invention can be used as a single-layer material. This single-layer material can be extruded onto a substrate layer.
A plastic film or paper web can, for example, be provided as the substrate layer.
In accordance with another further development of the invention, it is, however, also possible for the layer to be produced by the coextrusion process. In this case a substrate layer can be provided with the plastic layer with release properties not only on one side but also on both sides.
In accordance with another advantageous further development of the invention, the thickness of the plastic layer is in the 5 xcexcm range.
The release properties can be influenced even more if in accordance with another further development of the invention the plastic layer and/or the substrate film for its is embossed.